&NA;This study was carried out on 30 patients with symptomatic internal hemorrhoids and 20 normal controls. The anal sphincter pressure was studied before and after surgery. A significantly high anal pressure was found in all patients with symptomatic internal hemorrhoids, when compared with normal controls, and there was no relation between this increase and the degree of hemorrhoids. One week following surgery, this high pressure was reduced significantly and was not affected by the type of operation. Thus, this increase in resting anal pressure is due to an overactivity of the internal hemorrhoids, which is secondary to the presence of the hemorrhoidal mass.